Ten years ago, had you ever heard of the hand sanitizer Purell? It existed, but nobody really used it. Then one day, it was everywhere. Grocery stores placed dispensers at the door, nail salons gave it to clients, and people started carrying travel size bottles in their bags. With little advertising, how did Purell catch on?

Jonah Berger, an assistant professor of marketing at the University of Pennsylvania’s Wharton School of Business, has dedicated his career to answering that question. As he explains in his new book, Contagious: Why Things Catch On (Simon & Schuster, 2013), every viral product has six key features in common -- features that can be replicated to make any product go viral.

"People often think that contagious products just get lucky," Berger says. "But it's not luck and it’s not random. It's science."

According to Berger's research, specific circumstances and attributes empower consumers to share a given product. Any business can leverage those insights to create a viral hit. "You don't need a huge advertising budget," Berger says.

As many as half of consumers' purchasing decisions are driven by word of mouth marketing -- it's trustworthy and far more targeted than traditional advertising. Plus, the majority of those interactions happen offline, where advertisements can't reach. "Authenticity is a big reason word of mouth impacts behavior," Berger says.

To create a viral product that consumers are inspired to share authentically, incorporate these key elements.

1. Social currency. Consumers are more likely to adopt a product if it makes them feel special or ahead of the curve. For example, Gilt's exclusive sales helped it become one of the hottest online shopping sites.

2. Triggers. Products that catch on become part of our everyday lives, so successful products create reasons and reminders to return on a regular basis. For example, Facebook and Twitter drive you back to their sites every time they email you to say you have a new message or mention.

3. Emotional impact. People tend to evangelize a product if it affected them emotionally, whether it solved a stressful problem or brightened a bad day. For example, if a Buzzfeed article makes you laugh, you’ll likely share it with friends who need a lift.

4. Visibility. Giving a product a distinctive feature, such as a standout logo or color, helps consumers notice when others are using it. For example, you immediately recognize iPods because Apple made the headphones white when other companies all used black.

5. Practical value. A truly useful product that helps the user become more effective is more likely to be recommended often. For example, Evernote is very good at helping users remember and organize information, so it's often recommended for research.

6. Stories. If people are going to share your product, they need to be able to tell its story. That can be as simple as a clear statement about what the product does, or as complicated as a really interesting origin story. For example, people who buy TOMS shoes love telling others how one pair is donated for every pair you buy.

Creating a MAP will take no more than an hour of your time every month and will keep the lines of communication open, ensuring relationships with investors remain strong, and ultimately helping early-stage startups succeed.